融入LDPC纠错机制的认知无线电物理层认证分析

摘要

In this paper,the capacity of embedded primary transmitter authentication channel in cognitive radio is investigated.By employing the log-likelihood ratios(LLRs) of a tag bit and its approximation,we showed that the equivalent authentication channel observed by the secondary receiver can be viewed as a binary-input additive white Gaussian noise(BI-AWGN) channel.Then,we investigated the practical performance of the embedded authentication channel with the use of LDPC coding.With the approximate form of LLRs,we found that it performs very close to that of belief propagation decoding over the ideal BI-AWGN channel.Hence,we concluded that a good error-control coding scheme for a BI-AWGN channel is also good for embedded primary transmitter authentication channel,and the proposed approximate form of LLRs can be well exploited to facilitate the computation in practice with low complexity.%从信道纠错编码的角度来探讨认知无线电寄生认证信道的容量.首先,通过推导认证信道的对数似然比,给出了其简化计算方式,分析与仿真结果表明:简化计算与严格计算结果相仿,因而认证信道可等效为二元输入的加性高斯白噪声(BI-AWGN)信道.其次,基于对数似然比的简化形式,通过置信度传播迭代译码,考察了融入LDPC纠错机制的认证信道实际传输性能,仿真结果表明:实际简化译码的结果与理想BI-AWGN的译码性能无法区分.最终得出研究结论:认知无线电寄生认证信道可严格等效为BI-AWGN信道,因而可采用BI-AWGN信道设计的纠错编码来有效逼近寄生认证信道的传输极限.